Dealing with lost acknowledgements when power-saving

• US 20040223493A1
• Filed: 01/30/2004
• Published: 11/11/2004
• Est. Priority Date: 01/30/2003
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Incorporated
• Inventors: Kocherla, Srinivasa R., Krishnakumar, Anjur Sundaresan, Benveniste, Mathilde
• Granted Patent: US 8,009,600 B2
• Time in Patent Office: Days
• US Class Current: 370/394
• CPC Class Codes: H04L 1/1829 Arrangements specially adapted for the receiver end
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A novel method and apparatus for coping with lost acknowledgements from power-saving stations in local-area networks are disclosed. In particular, the illustrative embodiment modifies the access point'"'"'s and power-saving stations'"'"' protocols to prevent repeated lost acknowledgements from occurring. An access point, after transmitting the final downlink frame of a sequence to a station and receiving an acknowledgement from the station, transmits a “double acknowledgement” to the station. A power-saving station, after receiving the final downlink frame of a sequence and transmitting an acknowledgement to the access point, stays awake until one of the following occur: (i) the station receives a double acknowledgement, (ii) the station observes a frame transmitted from the access point to another station, or (iii) the station observes that the shared-communications channel of the local-area network is idle for a particular time interval.

Claims

1. A method comprising:

(a) receiving a final frame of a sequence of one or more frames;

(b) transmitting to the sender of said final frame an acknowledgement that acknowledges said first frame;

(c) receiving from the sender of said final frame a frame that acknowledges said acknowledgement; and

(d) entering, after (c), a reduced-power state.

2. The method of claim 1 wherein (a), (b), and (c) are via a shared-communications channel.

3. A method comprising:

(a) receiving a final frame of a sequence of one or more frames;

(b) observing, after (a), a frame transmitted to another party; and

(c) entering, after (b), a reduced-power state.

4. The method of claim 3 wherein (a) and (b) are via a shared-communications channel.

5. A method comprising:

(a) receiving a final frame of a sequence of one or more frames via a shared-communications channel;

(b) determining, after (a), that said shared-communications channel is idle for a time interval; and

(c) entering, after (b), a reduced-power state.

6. The method of claim 5 wherein said final frame is transmitted by an access point, and wherein said time interval is a Point Coordination Function InterFrame Spacing.

7. A method comprising:

(a) transmitting to a station a frame f in a sequence of one or more frames;

(b) receiving from said station an acknowledgement that acknowledges said frame f;

(c) transmitting to said station, after (b), a frame that acknowledges said acknowledgement when (i) said frame f is the final frame of said sequence, and (ii) said station is the last polled station during a contention-free period; and

(d) transmitting to said station, after (b), the frame following said frame f in said sequence when said frame f precedes the final frame of said sequence.

8. A method comprising:

(a) receiving a final frame of a sequence of one or more frames via a shared-communications channel;

(b) transmitting via said shared-communications channel an acknowledgement to the sender of said final frame, wherein said acknowledgement acknowledges said final frame;

(c) listening, after (b), to said shared-communications channel for a frame; and

(d) entering a reduced-power state when said frame acknowledges said acknowledgement.

9. The method of claim 8 further comprising:

(e) entering said reduced-power state when said frame is directed to another party.

10. The method of claim 8 further comprising:

(f) entering said reduced-power state when, during (c), said shared-communications channel is idle for a time interval.

11. An apparatus comprising:

a transceiver for;

receiving a final frame of a sequence of one or more frames,

transmitting to the sender of said final frame an acknowledgement that acknowledges said final frame, and

receiving from the sender of said final frame a frame that acknowledges said acknowledgement; and

a logic circuit for outputting, after said transceiver receives said frame, a signal that causes said transceiver to enter a reduced-power state.

12. The apparatus of claim 11 wherein said transceiver transmits and receives via a shared-communications channel.

13. An apparatus comprising:

a receiver for;

receiving a first signal, wherein said first signal comprises a final frame of a sequence of one or more frames directed to said apparatus, and

receiving, after said first signal, a second signal, wherein said second signal comprises a second frame that is directed to another party; and

a logic circuit for outputting, after said receiver receives said second signal, a third signal that causes said receiver to enter a reduced-power state.

14. The apparatus of claim 13 wherein said receiver receives said first signal and said second signal via a shared-communications channel.

15. An apparatus comprising:

a receiver for;

listening to a shared-communications channel, and

receiving, via said shared-communications channel, a final frame of a sequence of one or more frames; and

a logic circuit for;

determining, in conjunction with said receiver, that said shared-communications channel is idle for a time interval after said receiver receives said frame; and

outputting, after said determining, a signal that causes said receiver to enter a reduced-power state.

16. The apparatus of claim 15 wherein said frame is transmitted by an access point, and wherein said time interval is a Point Coordination Function InterFrame Spacing.

17. An apparatus comprising:

a transmitter for transmitting to a station a frame f of a sequence of one or more frames;

a receiver for receiving from said station an acknowledgement that acknowledges said frame f; and

a logic circuit for;

outputting, when said frame f is the final frame of said sequence and said station is the last polled station during a contention-free period, a signal that causes said transmitter to transmit a frame that acknowledges said acknowledgement, and

outputting, when said frame f precedes the final frame of said sequence, a signal that causes said transmitter to transmit the frame following said frame f in said sequence.

18. An apparatus comprising:

a transceiver for;

receiving a final frame of a sequence of one or more frames via a shared-communications channel,

transmitting to the sender of said final frame, via said shared-communications channel, an acknowledgement that acknowledges said final frame, and

listening, after transmitting said acknowledgement, to said shared-communications channel for a frame; and

a logic circuit for outputting, when said frame acknowledges said acknowledgement, a signal that causes said transceiver to enter a reduced-power state.

19. The apparatus of claim 18 wherein said logic circuit is also for outputting said signal when said frame is directed to another party.

20. The apparatus of claim 18 wherein said logic circuit is also for outputting said signal when, after said transceiver transmits said acknowledgement, said shared-communications channel is idle for a time interval.